a. Field of the Invention
The field of the invention relates generally to cardiac ablation, and, more particularly, to vascular occlusion during cardiac ablation.
b. Description of Related Art
Atrial fibrillation is a form of arrhythmia and results from disorganized electrical activity in the heart muscle, or myocardium. As a result of abnormalities in the heart's electrical activity, the heart does not beat effectively and it is not able to pump the blood out properly.
Ablation of the mitral isthmus, defined as a narrow region between the mitral annulus and the left inferior pulmonary vein ostium, appears to increase the success rate of treating chronic atrial fibrillation. However, it is difficult to create transmural lesions in this region, even though the myocardial thickness in the mitral isthmus is not particularly greater than in other regions of the left atrium. Incomplete or non-continuous lesions and/or unidirectional mitral isthmus block can be problematic as it may result in recurrence of arrhythmia and/or a proarrhythmic effect by slowing conduction through the mitral isthmus. High-power endocardial ablations, as well as delivery of radio frequency (RF) energy into the coronary sinus and the great cardiac vein (epicardial portion of the mitral isthmus), are frequently used to prevent incomplete lines. This combined epicardial/endocardial approach allows for bidirectional isthmus block to be achieved.